1. Field of the Invention
The present invention relates to an analysis apparatus such as a thermal analyzer, and in particular relates to an analysis apparatus for consecutively measuring a plurality of samples.
2. Description of Related Art
Measurement signals measured by an analysis apparatus include errors caused by various factors. It is therefore necessary to calibrate for errors included in measurement signals by carrying out device calibration using reference samples or reference materials in order to obtain a more precise measurement signal. For example, when carrying out measurements for temperature signals using a thermal analyzer for measuring properties of a sample while changing the temperature, error factors exist such as errors due to thermocoupling itself when measuring temperature, errors due to electrical circuit systems, and errors due to changes in heat transfer conditions due to differences in the type of sample container, measurement atmosphere or heating rate. As a result, in temperature calibration of a thermal analyzer, melting points are measured using one type or a plurality of types of high-purity metals as a reference material as the melting points of the metals is already known, calibration values are obtained from differences in documented values, and temperature signal calibration is carried out.
The content of these error factors changes according to measurement conditions but there are also error factors, the content of which do not change due to measurement conditions, error factors the content of which changes, and error factors that are themselves included as part of the conditions. Of the error factors occurring in the temperature signal of the aforementioned thermal analyzer, cases where the type of sample container, the measurement atmosphere and the heating rate themselves are changed as measurement conditions in line with the objective of the measurements. Therefore, in order to obtain a high-precision measurement signal, it is necessary to carry out device calibration under the same conditions as for actual measurements. However, the procedure for carrying out device calibration for the analysis apparatus is complex and time-consuming and it is difficult to carry out device calibration prior to every measurement.
Therefore, in related analysis apparatuses, calibration conditions obtained by carrying out device calibration under a plurality of types of measurement conditions in advance are saved in advance. Then, prior to starting measurement, means are provided for selecting calibration conditions appropriate for the measurement conditions from the saved calibration conditions.
Further, with a thermal analyzer, the influence of the type of sample container on the measurement precision is substantial amongst the aforementioned error factors. Means are therefore provided to preset calibration conditions for each type of sample container in advance, select the type of sample container at the condition setting prior to measurement, and automatically select preset calibration conditions.
When measurements are carried out for a plurality of samples using an autosampler etc., individual measurements are carried out under different measurement conditions and it is necessary to use calibration conditions in line with each of the measurement conditions. With related analysis apparatuses, when a plurality of measurements are carried out there are no means for designating different calibration conditions for each measurement, and a single calibration condition designated before starting is used in all measurements that are carried out consecutively.
Further, with thermal analyzers having means for automatically selecting calibration conditions preset according to the type of sample container, because the same calibration conditions can be used if the type of sample container is the same, it is not possible to measure by changing over calibration conditions based on conditions outside the preset types of sample container. Because of this, when a plurality of types of measurement are carried out using a related analysis apparatus, it is not possible to designate the most appropriate measuring conditions taking into account calibration of error factors other than the type of sample container and this becomes troublesome with regards to obtaining a highly precise measurement signal by carrying out measurements using average or typical calibration conditions.